/**
 * Licensed to the Apache Software Foundation (ASF) under one
 * or more contributor license agreements.  See the NOTICE file
 * distributed with this work for additional information
 * regarding copyright ownership.  The ASF licenses this file
 * to you under the Apache License, Version 2.0 (the
 * "License"); you may not use this file except in compliance
 * with the License.  You may obtain a copy of the License at
 *
 *     http://www.apache.org/licenses/LICENSE-2.0
 *
 * Unless required by applicable law or agreed to in writing, software
 * distributed under the License is distributed on an "AS IS" BASIS,
 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
 * See the License for the specific language governing permissions and
 * limitations under the License.
 */
package org.apache.zookeeper.server.quorum;

import java.io.IOException;
import java.util.HashMap;

import org.apache.zookeeper.jmx.MBeanRegistry;
import org.apache.zookeeper.server.DataTreeBean;
import org.apache.zookeeper.server.ServerCnxn;
import org.apache.zookeeper.server.ZKDatabase;
import org.apache.zookeeper.server.ZooKeeperServerBean;
import org.apache.zookeeper.server.persistence.FileTxnSnapLog;

/**
 * Parent class for all ZooKeeperServers for Learners
 */
public abstract class LearnerZooKeeperServer extends QuorumZooKeeperServer {
	public LearnerZooKeeperServer(FileTxnSnapLog logFactory, int tickTime, int minSessionTimeout, int maxSessionTimeout,
			DataTreeBuilder treeBuilder, ZKDatabase zkDb, QuorumPeer self) throws IOException {
		super(logFactory, tickTime, minSessionTimeout, maxSessionTimeout, treeBuilder, zkDb, self);
	}

	@Override
	public void createSessionTracker() {
		sessionTracker = new LearnerSessionTracker(this, getZKDatabase().getSessionWithTimeOuts(), self.getId());
	}

	/**
	 * Abstract method to return the learner associated with this server. Since the
	 * Learner may change under our feet (when QuorumPeer reassigns it) we can't
	 * simply take a reference here. Instead, we need the subclasses to implement
	 * this.
	 */
	abstract public Learner getLearner();

	/**
	 * Returns the id of the associated QuorumPeer, which will do for a unique id of
	 * this server.
	 */
	@Override
	public long getServerId() {
		return self.getId();
	}

	/**
	 * Returns the current state of the session tracker. This is only currently used
	 * by a Learner to build a ping response packet.
	 * 
	 */
	protected HashMap<Long, Integer> getTouchSnapshot() {
		if (sessionTracker != null) {
			return ((LearnerSessionTracker) sessionTracker).snapshot();
		}
		return new HashMap<Long, Integer>();
	}

	@Override
	protected void registerJMX() {
		// register with JMX
		try {
			jmxDataTreeBean = new DataTreeBean(getZKDatabase().getDataTree());
			MBeanRegistry.getInstance().register(jmxDataTreeBean, jmxServerBean);
		} catch (Exception e) {
			LOG.warn("Failed to register with JMX", e);
			jmxDataTreeBean = null;
		}
	}

	public void registerJMX(ZooKeeperServerBean serverBean, LocalPeerBean localPeerBean) {
		// register with JMX
		if (self.jmxLeaderElectionBean != null) {
			try {
				MBeanRegistry.getInstance().unregister(self.jmxLeaderElectionBean);
			} catch (Exception e) {
				LOG.warn("Failed to register with JMX", e);
			}
			self.jmxLeaderElectionBean = null;
		}

		try {
			jmxServerBean = serverBean;
			MBeanRegistry.getInstance().register(serverBean, localPeerBean);
		} catch (Exception e) {
			LOG.warn("Failed to register with JMX", e);
			jmxServerBean = null;
		}
	}

	@Override
	protected void revalidateSession(ServerCnxn cnxn, long sessionId, int sessionTimeout) throws IOException {
		getLearner().validateSession(cnxn, sessionId, sessionTimeout);
	}

	@Override
	protected void startSessionTracker() {
	}

	@Override
	protected void unregisterJMX() {
		// unregister from JMX
		try {
			if (jmxDataTreeBean != null) {
				MBeanRegistry.getInstance().unregister(jmxDataTreeBean);
			}
		} catch (Exception e) {
			LOG.warn("Failed to unregister with JMX", e);
		}
		jmxDataTreeBean = null;
	}

	protected void unregisterJMX(Learner peer) {
		// unregister from JMX
		try {
			if (jmxServerBean != null) {
				MBeanRegistry.getInstance().unregister(jmxServerBean);
			}
		} catch (Exception e) {
			LOG.warn("Failed to unregister with JMX", e);
		}
		jmxServerBean = null;
	}
}
